1. Technical Field
The invention relates generally to conveyor systems and, more particularly, to a conveyor system utilizing angled rollers for retaining an empty box on a conveyor belt as the box is transported along the conveyor belt. Specifically, the invention relates to a conveyor system that automatically adjusts to accommodate unassembled boxes having variations in size and delivers the boxes along a common index line and that utilizes angled rollers for retaining the boxes on the conveyor belt.
2. Background Information
Essentially all commercial goods travel through commerce enclosed in some type of packaging. Among the most common types of packaging are boxes (also referred to as cartons or cases) of a rectangular solid shape and that are typically manufactured of corrugated cardboard. Such boxes are of innumerable shapes and sizes suited to the specific needs of the packaging application. One such type of carton is a parallelepiped box with inward-turned flaps on at least the bottom thereof.
Unassembled parallelepiped boxes are typically cut from a single sheet of material and then formed into a generally tubular configuration having four sides. Each side terminates with a top flap and a bottom flap at opposite ends thereof. The top flaps and bottom flaps are folded inwardly and sealed to form top and bottom sides, respectively. Such boxes are typically shipped from a manufacturer in a flat configuration as blanks that must be assembled into a three-dimensional box prior to use. Such assembly can be by hand or through the use of a box erecting machine.
The flaps of a box are designated in the art as "major" and "minor" depending on their relative length. For instance, in a parallelepiped box having a length, a width, and a height, with the length and width being unequal, the major flaps are the two opposed flaps lying adjacent the longer of the length and width, with the minor flaps being the flaps adjacent the shorter of the length and the width. While many parallelepiped boxes have bottom-forming flaps and top-forming flaps, some parallelepiped boxes have only bottom-forming flaps, with the fully assembled box having an open top.
Parallelepiped boxes are assembled by first drawing the unassembled, flat box into a generally tubular rectangular shape. The minor flaps are each folded 90 degrees inward, with the major flaps then being folded 90 degrees inward and over the minor flaps. The flaps may then be sealed in place using glue, adhesive tape, gummed tape, or other such materials that are known and understood in the relevant art. In some situations, the bottom flaps are not sealed until after the box has been filled.
The bottom flaps of a parallelepiped box often are folded first with the top flaps being left open or unassembled so that the box can be filled with the appropriate contents. The box filling operation typically occurs on an open conveyor system. Such an open conveyor system typically includes a conveyor belt on which the boxes travel and sets of rollers on either side of the boxes parallel with the direction of belt travel to maintain boxes in the proper orientation as they travel down the conveyor belt for filling.
After a box has been filled, the final step is to fold and seal the top flaps of the box. The top flaps are assembled in a manner similar to the assembly of the bottom flaps, i.e., folding the minor flaps 90 degrees inward, folding the major flaps 90 degrees inward and over the minor flaps, and then sealing the major flaps in position with glue, adhesive tape, gummed tape, or the like. If the bottom flaps have not yet been sealed, they will typically be sealed at this point.
Such operations often are performed as part of an assembly line operation with the unfolded boxes being loaded into a magazine, each box being opened in turn and the bottom flaps thereof assembled to form a bottom. The boxes are then appropriately filled and the flaps thereof assembled.
When adhesive tape is utilized to seal the flaps of the box, the tape is typically delivered from a large roll attached to a tape head of the type known and understood in the relevant art. As indicated hereinbefore, the bottom flaps of a box may be folded prior to being filled and left unsealed until after the box has been filled and the top flaps have been folded into place. In such assembly lines, the bottom flaps and the top flaps of the boxes are typically sealed simultaneously by taping or gluing structures located both above and below the box assembly line.
One reason, among others, for performing the taping or gluing operations simultaneously on both the top and bottom flaps of a box is to facilitate replacement of tape rolls, refilling of glue reservoirs, etc., from a single location. Inasmuch as the boxes must typically be removed from the assembly line prior to replacing a tape roll, the removal of boxes from only one portion of the line while replacing the tape rolls on both the upper and lower taping mechanisms results in significant savings in cost and time. If the taping mechanisms for taping the top flaps and the bottom flaps are located at different points along the production line, boxes must be removed from both regions of the line to replace the tape rolls at those locations, thus requiring the expenditure of additional time and effort.
If the bottom flaps of a box are not sealed prior to being filled, the unsealed box typically must be held downward on the conveyor belt by a suitable structure, otherwise the combined elastic springback of the four bottom flaps will cause the box to rise up off the conveyor belt, often resulting in misalignments, jamming, and other conveyance problems. Such elastic springback is inherent in most materials, including those used to manufacture boxes. The elastic springback in the boxes is preferably overcome to assure continuous and reliable box conveyance and to prevent the interruptions and downtime to the production line resulting from boxes losing contact with the conveyer belt, becoming misaligned, and ultimately causing jams and other such problems. The unsealed boxed must be held against the conveyer belt prior to filling and must additionally be held subsequent to filling if the fill material is light or contains a great proportion of lightweight packing material that is of insufficient weight to overcome the aforementioned elastic springback.
One method known in the art of countering the elastic springback inherent in the folded but unsealed bottom flaps of a carton is to employ forward-angled rollers on either side of the boxes as they travel down the conveyor belt. The forward-angled rollers have the tendency to drive the box in a downward direction toward the conveyor belt as the box moves forward, thus retaining the box on the conveyor belt. Such forward-angled rollers have been used in other box-moving conveyor systems wherein it is desired to retain a box on a conveyor belt.
Box erecting machines and box conveyors of the type described above are rather complex and expensive machines that are permanently installed in production lines and are capable of being set up to assemble and transport boxes of different sizes. Such machines typically include adjustable guide rails that have rollers to maintain the boxes in proper orientation.
One such machine utilizes both a stationary guide and an adjustable guide that is adjusted to correspond with the width of the box being transported. One reason for designing machinery to contain a fixed guide and a moveable guide is to permit the boxes, as they are assembled and filled, to travel along a fixed, constant "index" line. Inasmuch as the cartons are assembled for the purpose of carrying goods, the goods must, at some point, be loaded into the boxes. Boxes traveling through a production line along a fixed index line are more easily filled than boxes that are delivered centered along a conveyor system inasmuch as centered boxes require a longer reach by the individual or the machinery that fills the box. Boxes traveling along a common index line can be filled directly from the index line with minimal reach and minimal wasted effort. Additionally, the use of a common index line for the filling of boxes expedites the setup of automated machinery used for filling such boxes. Such machinery has not, however, utilized forward-angled rollers to retain a box on a conveyor belt.
Another problem associated with erecting boxes in box erecting machines is that the standard tolerances of the box industry allow for varying dimensions such that each box has slightly varying width, length, and height dimensions. Although these varying dimensions do not create problems when the box is erected by hand, the varying dimensions can cause a box erecting machine to jam. In some boxes the dimensions may vary as much as 1/8 of an inch above or below the target dimension for a total of 1/4 of an inch of uncertainty in the dimension. If the rollers are adjusted to the nominal dimension, boxes smaller than the nominal dimension may not be held by the rollers, and boxes larger than the nominal dimension might jam between the rollers if the rollers are fixed and are unable to adjust automatically to accommodate the different sized boxes.
The invention disclosed in U.S. Pat. No. 5,735,378 to Sundquist discloses a conveyor system utilizing forward-angled rollers to hold a carton downward on a conveyor system as the carton is transported. While the invention disclosed in Sundquist has achieved success for the purposes disclosed therein, Sundquist does not disclose a carton conveyor system capable of delivering boxes of different sizes along a common index line and does not disclose a conveyor system that can automatically adjust to accommodate boxes having dimensional variations.
Thus, a need exists for a conveyor system that can retaining an empty box on a conveyor belt along a common index line, that can automatically adjust to accommodate the dimensional variations of boxes, and that can function cooperatively with other box erecting and box taping machines which utilize a common index line and which are known and understood in the relevant art.